Tandem batch feed and tandem batch collection apparatus for continuous pyrolysis of rubber and/or other hydrocarbon-based material

ABSTRACT

An apparatus for vacuum pyrolysis of rubber and/or other hydrocarbon material is provided. The apparatus includes tandem batch feed hoppers operated sequentially under vacuum to continuously feed the pyrolysis reactor, and tandem batch collection bins operated in sequence under vacuum to collect the reaction product from the reactor. A process for vacuum pyrolysis is also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority under 35 U.S.C. §119(e) to U.S.provisional application Serial No. 60/238,455, filed Oct. 10, 2000.

FIELD OF THE INVENTION

[0002] The present invention relates to a continuous feed/collectionapparatus for the vacuum pyrolysis of cuttings of rubber and/orhydrocarbon-based material, including hydrocarbon-contaminated soil, toyield a non-condensable fraction of combustible vapor; oil; and acarbonaceous solid residue.

BACKGROUND OF THE INVENTION

[0003] The treatment of rubber and plastics such as vehicle tiresplastic and rubber residues from shredded automobiles and RDF (RefuseDerived Fuel) is a major environmental problem. Economical vacuumpyrolysis of rubber and plastics cuttings has been attempted for thepast several decades. However, rubber becomes sticky and causes cloggingof conventional transport systems. Some systems attempt to overcome thisproblem by using high temperature reactors or by recycling a portion ofproduct residue to coat the sticky material.

[0004] U.S. Pat. No. 4,740,270 describes a process for the vacuumpyrolysis of scrap tires in which fire cuttings are moved in amulti-tray reactor with a conventional transportation system from anupper tray to a lower tray. The tire cuttings are shifted from the toptray to the bottom tray along a temperature gradient from 392° F. andpeaking at 932° F. Thus, the tire cuttings are heated up whilecontinuously moving down. Other patented processes, which utilize hightemperatures, are described in U.S. Pat. Nos. 6,046,370 and 4,740,270.

[0005] U.S. Pat. No. 4,084,521 to Herbold et al. discloses a method andapparatus for pyrolysis of waste products such as tires. The apparatusincludes a charging hopper that has two airtight chambers connected oneafter another to form an airlock. Also, a door or delivery flap isbiased by counter-weight in order to crush practically all of theresidual material before it can drop past a delivery flap U.S. Pat. No.6,046,370 to Affolter et al. describes a process for vacuum pyrolysis ofrubber and plastic cuttings in which a portion of the producedcarbonaceous residue is added back to eliminate sticking of the hotproduct during processing. The process is run at a reactor temperatureof 842° F. to 1022° F. Lack of commercial success of many prior artmethods has led to the continued need for new methods and apparatus forvacuum pyrolysis of rubber and other hydrocarbon materials.

SUMMARY OF THE INVENTION

[0006] The present invention relates to a continuous feed/continuouscollection apparatus for the treatment of rubber and/or otherhydrocarbon-based material by vacuum pyrolysis of cuttings of thematerial to yield fractions of combustible vapor, oil, wire, andcarbonaceous solid residue. The system includes a plurality of tandemfeed and tandem collection bins that are designed to maintain thereaction under vacuum, while allowing a continuous flow of reactants andproducts to and from the reactor.

[0007] It is an object of the present invention to provide method andapparatus for vacuum pyrolysis of rubber and other hydrocarbonmaterials.

[0008] It is a further object of the present invention to provide anapparatus for vacuum pyrolysis of rubber and hydrocarbon materialshaving inlet and outlet bins maintained at vacuum pressure.

[0009] It is an additional object of the present invention to provide anapparatus for vacuum pyrolysis of rubber and hydrocarbon materialshaving inlet and outlet bins maintained at a vacuum that allows forcontinuous feed and operation while maintaining vacuum conditions.

[0010] These and other objects of the invention will become readilyapparent from the following drawings, detailed description and appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The invention is further illustrated by the following non-limiteddrawings in which:

[0012]FIG. 1 schematically shows a vacuum pyrolysis apparatus havingcontinuous feed/continuous collection apparatus according to the presentinvention; and

[0013] FIGS. 2(a)-(b) schematically show tandem feed and tandemcollection bins according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention provides for an apparatus and process forthe treatment of rubber and plastics by vacuum pyrolysis of cuttings ofrubber and plastics to yield a non-condensable fraction of combustiblevapor; oil; and a carbonaceous solid residue.

[0015] In one aspect of the present invention, the invention provides anapparatus for the treatment of rubber, plastics, and/or otherhydrocarbon-based material comprising tandem feed bins alternatingbetween vacuum and atmospheric pressure to load the reactor in acontinuous fashion. Likewise, the apparatus may also utilize tandemcollection bins alternating between vacuum and atmospheric pressure tocollect the product in a continuous fashion.

[0016] In an additional aspect of the invention, the present inventionprovides an apparatus for reclamation and recovery of constituents ofdiscarded vehicle tires and other rubber-based materials, includingorganic and inorganic materials, for reuse or environmentally-safedisposal. This apparatus comprises a feed system for transferringrubber-based material to an inlet of a low temperature reactor chamberhaving activation, decomposition, and completion zones, and having ahelicoid auger for transferring pieces of the rubber orhydrocarbon-based material from the reactor inlet and solid product froma reactor outlet. The inlet and outlet bins are positioned at each endof the low temperature reactor chamber. The apparatus further comprisesa solid material recovery system, and a vapor recovery system forrecovering vapor from the decomposition zone of reactor chamber.

[0017] The vapor recovery system comprises a heat exchanger forcondensing vapor from the low temperature reactor chamber, aliquid/vapor separator for separating liquids condensed in the heatexchanger, and a vacuum pump for removing vapor from the decompositionzone of the reactor chamber.

[0018] A catalyst may be used to provide a non-sticking product andallows a helical auger reactor to be used to transport the reactants. Atleast a portion of the carbonaceous solid residue may be mechanicallymixed with the rubber and plastic cuttings before and during pyrolysis.The mechanical mixing facilitates achieving 1) a homogeneous solid mass;(2) a high transfer of heat from a reactor shell into the solid product;and (3) a reduction of the reaction time.

[0019] As shown in FIG. 2(a), the reactor is fed under vacuum in acontinuous manner from one hopper while a second hopper is filled atatmospheric pressure. Just before the first hopper is empty, the secondhopper is sealed and put under vacuum. The full, second hopper is thenput into operation as the first hopper is opened and filled. This tandemfill and vacuum operation allows the reactor to be fed in a continuousmanner. At the reactor output, a similar system is set up to empty thereactor in a continuous manner as shown in FIG. 2(b).

[0020] In a preferred embodiment, pre-dried rubber enters feeder binsand a catalytic compound is added to intensify the rubber liquefactionprocess. The rubber is transferred, by helicoid augers, from the feederbins through a controlled temperature reactor chamber and into outputbins. The reactor chamber is maintained under moderate vacuum and isheated to maintain temperatures which are varied spatially over thelength of the reactor chamber, varying between ambient temperature and atemperature required for the process. A primary economic benefit is thatthe spatially-varying temperature profile reactor is designed to takeadvantage of the exothermic properties of the pyrolysis reaction toimprove the efficiency of the process.

[0021] A feeder and recovery system removes the vapor from the reactorchamber while maintaining the system operation under vacuum. The vaporpasses through a heat exchanger and separator where the liquidhydrocarbon product is removed and stored. The vapor is compressed andstored or recycled to augment the fuel used to heat the reactor. Thesolid residue is separated by an electromagnetic process into carbonblack/carbonaceous residue and wire. The carbon is further processedthrough granulating equipment.

[0022] An example of a continuous feed system is shown in FIG. 1.Shredded rubber 30 or other hydrocarbon material and a catalyst 35 aremoved into inlet bins or feed hoppers 40 by means of a conveyor belt 45or other loading apparatus. The elongated reaction chamber 50 is heatedat both ends by gas burner 55 and gas burner 60. The hydrocarbonmaterial is heated in the activation zone 65, and then moves by means ofa helicoid auger 70 to the decomposition zone 73, where the exothermicportion of the reaction occurs. As the reaction slows, the hydrocarbonmaterial is moved by means of the auger to the completion zone 75, afterwhich solid residue moves into the outlet bins 80 to a solid materialrecovery system 85 to yield carbon black and steel, if initiallypresent. Vapors 90 are continuously drawn off and condensed into oil 95by a heat exchanger or oil condensers 100 or burned as fuel during thereaction. A vacuum pump 105 draws off the vapors and maintains a vacuumduring the course of the reaction.

[0023] In yet another aspect of the present invention, the inventionprovides a process for treating rubber and/or hydrocarbon-based materialby vacuum pyrolysis. The process comprises transferring rubber and/orhydrocarbon-based material to the inlet of a low-temperature reactorchamber by a plurality of hoppers operated sequentially in vacuum and atatmospheric pressure. The rubber and/or hydrocarbon-based material isthen vacuum pyrolyzed, thereby yielding a carbon black/carbonaceoussolid residue, a liquid hydrocarbon product, wire, and a non-condensablecombustible vapor. The rubber and/or hydrocarbon-based material can befragmented to approximately 10×10 inch or smaller cuttings; previousseparation of cords and steel threads is not required. The reactor isheated to control the pyrolysis temperature, and spatial control of thedesired reaction temperature is maintained throughout the activation,decomposition and completion zones of the reactor chamber.

[0024] The foregoing disclosure has been set forth merely to illustratethe invention and is not intended to be limiting. Since modifications ofthe disclosed embodiments incorporating the spirit and substance of theinvention may occur to persons skilled in the art, the invention shouldbe construed to include everything within the scope of the appendedclaims and equivalents thereof.

What is claimed is:
 1. A continuous feed/continuous collection apparatusfor pyrolysis of rubber and/or hydrocarbon-based material, comprising: afeed system for transferring rubber and/or hydrocarbon-based materialcuttings to an inlet of a low temperature reactor chamber, wherein saidfeed system comprises a plurality of hoppers operated in sequence, eachhopper having a vacuum-sealable slide valve adjacent a top and a bottomof the hopper.
 2. A continuous feed/continuous collection apparatusaccording to claim 1, further comprising a continuous transport systemwithin the reactor chamber that moves a reaction product throughspatially varying temperature zones.
 3. A continuous feed/continuouscollection apparatus according to claim 1, further comprising acollection system for collecting a solid reaction product from a reactorchamber outlet.
 4. An apparatus for reclamation and recovery ofconstituents of discarded vehicle tires and other rubber-based materialsincluding organic and inorganic materials for reuse orenvironmentally-safe disposal, comprising: a feed system fortransferring rubber-based material to an inlet of a low temperaturereactor chamber, said low temperature reactor chamber having activation,decomposition, and completion zones and having a helicoid auger fortransferring pieces of the rubber-based material from the reactor inletand solid product from a reactor outlet; inlet and outlet binspositioned at each end of the low temperature reactor chamber; a solidmaterial recovery system; and a vapor recovery system for recoveringvapor from the decomposition zone of said low temperature reactorchamber.
 5. An apparatus according to claim 4, wherein said vaporrecovery system comprises: a heat exchanger for condensing vapor fromsaid low temperature reactor chamber; a liquid/vapor separator forseparating liquids condensed in said heat exchanger; and a vacuum pumpfor removing vapor from the decomposition zone of said low temperaturereactor chamber through said heat exchanger and said liquid/vaporseparator and maintaining a vacuum in said low temperature reactorchamber.
 6. A continuous feed/continuous collection apparatus accordingto claim 2, wherein said continuous transport system comprises ahelicoid auger.
 7. A process for treating rubber and/orhydrocarbon-based material by vacuum pyrolysis, comprising: transferringrubber and/or hydrocarbon-based material to an inlet of alow-temperature reactor chamber by a plurality of hoppers operatedsequentially in vacuum and at atmospheric pressure; vacuum pyrolyzingthe rubber and/or hydrocarbon-based material, thereby yielding a carbonblack/carbonaceous solid residue, a liquid hydrocarbon product, wire,and a non-condensable combustible vapor.
 8. A process according to claim7, further comprising fragmenting the rubber and/or hydrocarbon-basedmaterial to approximately 10×10 inch or smaller cuttings.
 9. A processaccording to claim 7, further comprising fragmenting the rubber and/orhydrocarbon-based material without previous separation of cords andsteel threads.
 10. A process according to claim 7, further comprisingheating the reactor to control a pyrolysis temperature.
 11. A processaccording to claim 10, further comprising maintaining the pyrolysistemperature through controlled spatially heating of the reactor tomaintain a reaction temperature.
 12. A process according to claim 7,wherein the rubber or hydrocarbon-based material comprises discardedvehicle tires.